NEW YORK (CNNMoney.com) - A housing-price drop would not be bad for everyone. In fact, many canny real-estate Investors have been hoping for just such a hit.

"You can make a fortune in a Falling market," says Hugh Bromma, CEO of Entrust Administration and author of "How to Invest in Real Estate and Pay Little or No Taxes."

You do it by buying low. Investors can build up Rental property portfolios more easily in down markets -- if their initial pay out is smaller, they can more likely turn a profit on rents.

"You always want an investment property to make money from the get-go -- always, always, always," says Bromma.

That means that rents must exceed expenses every month. It's even more important when prices are falling than when they're going up.

"If you don't buy a rental right," says Erwin Jackson, a Florida landlord, "by the time you pay the maintenance, insurance, taxes, and everything else, you won't have any money."........